Technologies

The SELEX Galileo facility at Southampton UK is a Centre of Excellence for infrared detectors. The site opened in 1956 and now employs approximately 200 people.  We are world leaders in the research and development of advanced detector technology for military, industrial, and space applications. It is the only facility of its kind in the UK.
 
Materials technology is at the heart of our capability and is of strategic importance. Our materials group specialises in the crystal growth of Mercury Cadmium Telluride (MCT), a narrow-gap semiconductor that is famously difficult to grow in the form of high quality single crystals but remains the material of choice for high performance infrared detectors worldwide. The team are responsible for metal organic vapour phase epitaxy (MOVPE), liquid phase epitaxy (LPE), and bulk crystal growth by the Bridgman method and the accelerated crucible rotation technique (ACRT).
 
The MCT crystals are processed into detector arrays in our two clean rooms, using a range of semiconductor processing techniques that have been adapted to this fragile material. We use polishing techniques, wet and dry etching, vacuum deposition for passivation, electroding, and optical coating, and indium bump bonding.
 
Our R&D department employs scientists and engineers who combine a wide range of skills and knowledge in physics, chemistry, and electronics, and has internationally recognised experts in the infrared field. It has a long history of collaboration with government laboratories and generates R&D funding through a mixture of private venture and competitive tendering. We develop new detector designs and manufacturing processes. In recent years, we have introduced multilayer device structures containing heterojunction photodiodes. These structures can be adapted to a wide range of infrared wavelengths and even to multi-colour infrared operation.
 
Modern infrared detectors contain an integrated circuit at the focal plane to multiplex and read out the analogue data stream. The integrated circuit design team produces full custom designs for our detector arrays using Cadence design tools.
 
High performance MCT detectors are operated around 80K to minimise thermally generated currents in the narrow-gap semiconductor, and the cooling is provided by miniature Stirling engines or sometimes Joule-Thomson coolers. This requirement drives the need for hermetically sealed vacuum encapsulations that exclude the atmosphere and insulate the detector array for efficient cooling, in addition to providing a robust package that will survive harsh environments. The product design group provides specialist skills in encapsulation design, cryogenics, and vacuum technology. Specialised encapsulation techniques include laser welding, cold welding, wire bonding, brazing, vacuum sealing, soldering, adhesives, and glass-to-metal seals.